The overall level of illicit drug use does not depend on access to the purported gateway substances, whether alcohol/tobacco or cannabis, as would be expected if the GH were true. The “gateway” role of alcohol is also refuted by the evidence that whereas the aldehyde dehydrogenase deficiency is related to lower rates of drinking, it does not predict lower rates of non-alcohol substance use (Irons et al., 2007). Early protection against, or delays in, tobacco use onset also do not result in reduced risk of involvement with cannabis or other illegal drugs (Furr-Holden et al., 2004).
